/*
 * File:        KeyTable.js
 * Version:     1.1.6
 * CVS:         $Idj$
 * Description: Keyboard navigation for HTML tables
 * Author:      Allan Jardine (www.sprymedia.co.uk)
 * Created:     Fri Mar 13 21:24:02 GMT 2009
 * Modified:    $Date$ by $Author$
 * Language:    Javascript
 * License:     GPL v2 or BSD 3 point style
 * Project:     Just a little bit of fun :-)
 * Contact:     www.sprymedia.co.uk/contact
 *
 * Copyright 2009-2010 Allan Jardine, all rights reserved.
 *
 */


function KeyTable ( oInit )
{
    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * API parameters
     * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

    /*
     * Variable: block
     * Purpose:  Flag whether or not KeyTable events should be processed
     * Scope:    KeyTable - public
     */
    this.block = false;

    /*
     * Variable: event
     * Purpose:  Container for all event application methods
     * Scope:    KeyTable - public
     * Notes:    This object contains all the public methods for adding and removing events - these
     *           are dynamically added later on
     */
    this.event = {
        "remove": {}
    };


    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * API methods
     * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

    /*
     * Function: fnGetCurrentPosition
     * Purpose:  Get the currently focused cell's position
     * Returns:  array int: [ x, y ]
     * Inputs:   void
     */
    this.fnGetCurrentPosition = function ()
    {
        return [ _iOldX, _iOldY ];
    };


    /*
     * Function: fnGetCurrentData
     * Purpose:  Get the currently focused cell's data (innerHTML)
     * Returns:  string: - data requested
     * Inputs:   void
     */
    this.fnGetCurrentData = function ()
    {
        return _nOldFocus.innerHTML;
    };


    /*
     * Function: fnGetCurrentTD
     * Purpose:  Get the currently focused cell
     * Returns:  node: - focused element
     * Inputs:   void
     */
    this.fnGetCurrentTD = function ()
    {
        return _nOldFocus;
    };


    /*
     * Function: fnSetPosition
     * Purpose:  Set the position of the focused cell
     * Returns:  -
     * Inputs:   int:x - x coordinate
     *           int:y - y coordinate
     * Notes:    Thanks to Rohan Daxini for the basis of this function
     */
    this.fnSetPosition = function( x, y )
    {
        if ( typeof x == 'object' && x.nodeName )
        {
            _fnSetFocus( x );
        }
        else
        {
            _fnSetFocus( _fnCellFromCoords(x, y) );
        }
    };


    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Private parameters
     * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

    /*
     * Variable: _nBody
     * Purpose:  Body node of the table - cached for renference
     * Scope:    KeyTable - private
     */
    var _nBody = null;

    /*
     * Variable:
     * Purpose:
     * Scope:    KeyTable - private
     */
    var _nOldFocus = null;

    /*
     * Variable: _iOldX and _iOldY
     * Purpose:  X and Y coords of the old elemet that was focused on
     * Scope:    KeyTable - private
     */
    var _iOldX = null;
    var _iOldY = null;

    /*
     * Variable: _that
     * Purpose:  Scope saving for 'this' after a jQuery event
     * Scope:    KeyTable - private
     */
    var _that = null;

    /*
     * Variable: sFocusClass
     * Purpose:  Class that should be used for focusing on a cell
     * Scope:    KeyTable - private
     */
    var _sFocusClass = "focus";

    /*
     * Variable: _bKeyCapture
     * Purpose:  Flag for should KeyTable capture key events or not
     * Scope:    KeyTable - private
     */
    var _bKeyCapture = false;

    /*
     * Variable: _oaoEvents
     * Purpose:  Event cache object, one array for each supported event for speed of searching
     * Scope:    KeyTable - private
     */
    var _oaoEvents = {
        "action": [],
        "esc": [],
        "focus": [],
        "blur": []
    };

    /*
     * Variable: _oDatatable
     * Purpose:  DataTables object for if we are actually using a DataTables table
     * Scope:    KeyTable - private
     */
    var _oDatatable = null;

    var _bForm;
    var _nInput;
    var _bInputFocused = false;


    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Private methods
     * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */

    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Key table events
     */

    /*
     * Function: _fnEventAddTemplate
     * Purpose:  Create a function (with closure for sKey) event addition API
     * Returns:  function: - template function
     * Inputs:   string:sKey - type of event to detect
     */
    function _fnEventAddTemplate( sKey )
    {
        /*
         * Function: -
         * Purpose:  API function for adding event to cache
         * Returns:  -
         * Inputs:   1. node:x - target node to add event for
         *           2. function:y - callback function to apply
         *         or
         *           1. int:x - x coord. of target cell (can be null for live events)
         *           2. int:y - y coord. of target cell (can be null for live events)
         *           3. function:z - callback function to apply
         * Notes:    This function is (interally) overloaded (in as much as javascript allows for
         *           that) - the target cell can be given by either node or coords.
         */
        return function ( x, y, z ) {
            if ( (x===null || typeof x == "number") &&
                (y===null || typeof y == "number") &&
                typeof z == "function" )
            {
                _fnEventAdd( sKey, x, y, z );
            }
            else if ( typeof x == "object" && typeof y == "function" )
            {
                var aCoords = _fnCoordsFromCell( x );
                _fnEventAdd( sKey, aCoords[0], aCoords[1], y );
            }
            else
            {
                alert( "Unhandable event type was added: x" +x+ "  y:" +y+ "  z:" +z );
            }
        };
    }


    /*
     * Function: _fnEventRemoveTemplate
     * Purpose:  Create a function (with closure for sKey) event removal API
     * Returns:  function: - template function
     * Inputs:   string:sKey - type of event to detect
     */
    function _fnEventRemoveTemplate( sKey )
    {
        /*
         * Function: -
         * Purpose:  API function for removing event from cache
         * Returns:  int: - number of events removed
         * Inputs:   1. node:x - target node to remove event from
         *           2. function:y - callback function to apply
         *         or
         *           1. int:x - x coord. of target cell (can be null for live events)
         *           2. int:y - y coord. of target cell (can be null for live events)
         *           3. function:z - callback function to remove - optional
         * Notes:    This function is (interally) overloaded (in as much as javascript allows for
         *           that) - the target cell can be given by either node or coords and the function
         *           to remove is optional
         */
        return function ( x, y, z ) {
            if ( (x===null || typeof arguments[0] == "number") &&
                (y===null || typeof arguments[1] == "number" ) )
            {
                if ( typeof arguments[2] == "function" )
                {
                    _fnEventRemove( sKey, x, y, z );
                }
                else
                {
                    _fnEventRemove( sKey, x, y );
                }
            }
            else if ( typeof arguments[0] == "object" )
            {
                var aCoords = _fnCoordsFromCell( x );
                if ( typeof arguments[1] == "function" )
                {
                    _fnEventRemove( sKey, aCoords[0], aCoords[1], y );
                }
                else
                {
                    _fnEventRemove( sKey, aCoords[0], aCoords[1] );
                }
            }
            else
            {
                alert( "Unhandable event type was removed: x" +x+ "  y:" +y+ "  z:" +z );
            }
        };
    }

    /* Use the template functions to add the event API functions */
    for ( var sKey in _oaoEvents )
    {
        if ( sKey )
        {
            this.event[sKey] = _fnEventAddTemplate( sKey );
            this.event.remove[sKey] = _fnEventRemoveTemplate( sKey );
        }
    }


    /*
     * Function: _fnEventAdd
     * Purpose:  Add an event to the internal cache
     * Returns:  -
     * Inputs:   string:sType - type of event to add, given by the available elements in _oaoEvents
     *           int:x - x-coords to add event to - can be null for "blanket" event
     *           int:y - y-coords to add event to - can be null for "blanket" event
     *           function:fn - callback function for when triggered
     */
    function _fnEventAdd( sType, x, y, fn )
    {
        _oaoEvents[sType].push( {
            "x": x,
            "y": y,
            "fn": fn
        } );
    }


    /*
     * Function: _fnEventRemove
     * Purpose:  Remove an event from the event cache
     * Returns:  int: - number of matching events removed
     * Inputs:   string:sType - type of event to look for
     *           node:nTarget - target table cell
     *           function:fn - optional - remove this function. If not given all handlers of this
     *             type will be removed
     */
    function _fnEventRemove( sType, x, y, fn )
    {
        var iCorrector = 0;

        for ( var i=0, iLen=_oaoEvents[sType].length ; i<iLen-iCorrector ; i++ )
        {
            if ( typeof fn != 'undefined' )
            {
                if ( _oaoEvents[sType][i-iCorrector].x == x &&
                    _oaoEvents[sType][i-iCorrector].y == y &&
                    _oaoEvents[sType][i-iCorrector].fn == fn )
                {
                    _oaoEvents[sType].splice( i-iCorrector, 1 );
                    iCorrector++;
                }
            }
            else
            {
                if ( _oaoEvents[sType][i-iCorrector].x == x &&
                    _oaoEvents[sType][i-iCorrector].y == y )
                {
                    _oaoEvents[sType].splice( i, 1 );
                    return 1;
                }
            }
        }
        return iCorrector;
    }


    /*
     * Function: _fnEventFire
     * Purpose:  Look thought the events cache and fire off the event of interest
     * Returns:  int:iFired - number of events fired
     * Inputs:   string:sType - type of event to look for
     *           int:x - x coord of cell
     *           int:y - y coord of  ell
     * Notes:    It might be more efficient to return after the first event has been tirggered,
     *           but that would mean that only one function of a particular type can be
     *           subscribed to a particular node.
     */
    function _fnEventFire ( sType, x, y )
    {
        var iFired = 0;
        var aEvents = _oaoEvents[sType];
        for ( var i=0 ; i<aEvents.length ; i++ )
        {
            if ( (aEvents[i].x == x     && aEvents[i].y == y    ) ||
                (aEvents[i].x === null && aEvents[i].y == y    ) ||
                (aEvents[i].x == x     && aEvents[i].y === null ) ||
                (aEvents[i].x === null && aEvents[i].y === null )
                )
            {
                aEvents[i].fn( _fnCellFromCoords(x,y), x, y );
                iFired++;
            }
        }
        return iFired;
    }



    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Focus functions
     */

    /*
     * Function: _fnSetFocus
     * Purpose:  Set focus on a node, and remove from an old node if needed
     * Returns:  -
     * Inputs:   node:nTarget - node we want to focus on
     *           bool:bAutoScroll - optional - should we scroll the view port to the display
     */
    function _fnSetFocus( nTarget, bAutoScroll )
    {
        /* If node already has focus, just ignore this call */
        if ( _nOldFocus == nTarget )
        {
            return;
        }

        if ( typeof bAutoScroll == 'undefined' )
        {
            bAutoScroll = true;
        }

        /* Remove old focus (with blur event if needed) */
        if ( _nOldFocus !== null )
        {
            _fnRemoveFocus( _nOldFocus );
        }

        /* Add the new class to highlight the focused cell */
        jQuery(nTarget).addClass( _sFocusClass );

        /* If it's a DataTable then we need to jump the paging to the relevant page */
        var oSettings;
        if ( _oDatatable )
        {
            oSettings = _oDatatable.fnSettings();
            var iRow = _fnFindDtCell( nTarget )[1];
            var bKeyCaptureCache = _bKeyCapture;

            /* Page forwards */
            while ( iRow >= oSettings.fnDisplayEnd() )
            {
                if ( oSettings._iDisplayLength >= 0 )
                {
                    /* Make sure we are not over running the display array */
                    if ( oSettings._iDisplayStart + oSettings._iDisplayLength < oSettings.fnRecordsDisplay() )
                    {
                        oSettings._iDisplayStart += oSettings._iDisplayLength;
                    }
                }
                else
                {
                    oSettings._iDisplayStart = 0;
                }
                _oDatatable.oApi._fnCalculateEnd( oSettings );
            }

            /* Page backwards */
            while ( iRow < oSettings._iDisplayStart )
            {
                oSettings._iDisplayStart = oSettings._iDisplayLength>=0 ?
                    oSettings._iDisplayStart - oSettings._iDisplayLength :
                    0;

                if ( oSettings._iDisplayStart < 0 )
                {
                    oSettings._iDisplayStart = 0;
                }
                _oDatatable.oApi._fnCalculateEnd( oSettings );
            }

            /* Re-draw the table */
            _oDatatable.oApi._fnDraw( oSettings );

            /* Restore the key capture */
            _bKeyCapture = bKeyCaptureCache;
        }

        /* Cache the information that we are interested in */
        var aNewPos = _fnCoordsFromCell( nTarget );
        _nOldFocus = nTarget;
        _iOldX = aNewPos[0];
        _iOldY = aNewPos[1];

        var iViewportHeight, iViewportWidth, iScrollTop, iScrollLeft, iHeight, iWidth, aiPos;
        if ( bAutoScroll )
        {
            /* Scroll the viewport such that the new cell is fully visible in the rendered window */
            iViewportHeight = document.documentElement.clientHeight;
            iViewportWidth = document.documentElement.clientWidth;
            iScrollTop = document.body.scrollTop || document.documentElement.scrollTop;
            iScrollLeft = document.body.scrollLeft || document.documentElement.scrollLeft;
            iHeight = nTarget.offsetHeight;
            iWidth = nTarget.offsetWidth;
            aiPos = _fnGetPos( nTarget );

            /* Correct viewport positioning for vertical scrolling */
            if ( aiPos[1]+iHeight > iScrollTop+iViewportHeight )
            {
                /* Displayed element if off the bottom of the viewport */
                _fnSetScrollTop( aiPos[1]+iHeight - iViewportHeight );
            }
            else if ( aiPos[1] < iScrollTop )
            {
                /* Displayed element if off the top of the viewport */
                _fnSetScrollTop( aiPos[1] );
            }

            /* Correct viewport positioning for horizontal scrolling */
            if ( aiPos[0]+iWidth > iScrollLeft+iViewportWidth )
            {
                /* Displayed element is off the bottom of the viewport */
                _fnSetScrollLeft( aiPos[0]+iWidth - iViewportWidth );
            }
            else if ( aiPos[0] < iScrollLeft )
            {
                /* Displayed element if off the Left of the viewport */
                _fnSetScrollLeft( aiPos[0] );
            }
        }

        /* Take account of scrolling in DataTables 1.7 */
        if ( _oDatatable && typeof oSettings.oScroll != 'undefined' &&
            (oSettings.oScroll.sX !== "" || oSettings.oScroll.xY !== "") )
        {
            var dtScrollBody = oSettings.nTable.parentNode;
            iViewportHeight = dtScrollBody.clientHeight;
            iViewportWidth = dtScrollBody.clientWidth;
            iScrollTop = dtScrollBody.scrollTop;
            iScrollLeft = dtScrollBody.scrollLeft;
            iHeight = nTarget.offsetHeight;
            iWidth = nTarget.offsetWidth;

            /* Correct for vertical scrolling */
            if ( nTarget.offsetTop + iHeight > iViewportHeight+iScrollTop )
            {
                dtScrollBody.scrollTop = (nTarget.offsetTop + iHeight) - iViewportHeight;
            }
            else if ( nTarget.offsetTop < iScrollTop )
            {
                dtScrollBody.scrollTop = nTarget.offsetTop;
            }

            /* Correct for horizontal scrolling */
            if ( nTarget.offsetLeft + iWidth > iViewportWidth+iScrollLeft )
            {
                dtScrollBody.scrollLeft = (nTarget.offsetLeft + iWidth) - iViewportWidth;
            }
            else if ( nTarget.offsetLeft < iScrollLeft )
            {
                dtScrollBody.scrollLeft = nTarget.offsetLeft;
            }
        }

        /* Fire of the focus event if there is one */
        _fnEventFire( "focus", _iOldX, _iOldY );
    }


    /*
     * Function: _fnBlur
     * Purpose:  Blur focus from the whole table
     * Returns:  -
     * Inputs:   -
     */
    function _fnBlur()
    {
        _fnRemoveFocus( _nOldFocus );
        _iOldX = null;
        _iOldY = null;
        _nOldFocus = null;
        _fnReleaseKeys();
    }


    /*
     * Function: _fnRemoveFocus
     * Purpose:  Remove focus from a cell and fire any blur events which are attached
     * Returns:  -
     * Inputs:   node:nTarget - cell of interest
     */
    function _fnRemoveFocus( nTarget )
    {
        jQuery(nTarget).removeClass( _sFocusClass );
        _fnEventFire( "blur", _iOldX, _iOldY );
    }


    /*
     * Function: _fnClick
     * Purpose:  Focus on the element that has been clicked on by the user
     * Returns:  -
     * Inputs:   event:e - click event
     */
    function _fnClick ( e )
    {
        var nTarget = this;
        while ( nTarget.nodeName != "TD" )
        {
            nTarget = nTarget.parentNode;
        }

        _fnSetFocus( nTarget );
        _fnCaptureKeys();
    }



    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Key events
     */

    /*
     * Function: _fnKey
     * Purpose:  Deal with a key events, be it moving the focus or return etc.
     * Returns:  bool: - allow browser default action
     * Inputs:   event:e - key event
     */
    function _fnKey ( e )
    {
        /* If user or system has blocked KeyTable from doing anything, just ignore this event */
        if ( _that.block || !_bKeyCapture )
        {
            return true;
        }

        /* If a modifier key is pressed (exapct shift), ignore the event */
        if ( e.metaKey || e.altKey || e.ctrlKey )
        {
            return true;
        }
        var
            x, y,
            iTableWidth = _nBody.getElementsByTagName('tr')[0].getElementsByTagName('td').length,
            iTableHeight;

        /* Get table height and width - done here so as to be dynamic (if table is updated) */
        if ( _oDatatable )
        {
            /*
             * Locate the current node in the DataTable overriding the old positions - the reason for
             * is is that there might have been some DataTables interaction between the last focus and
             * now
             */
            var oSettings = _oDatatable.fnSettings();
            iTableHeight = oSettings.aiDisplay.length;

            var aDtPos = _fnFindDtCell( _nOldFocus );
            if ( aDtPos === null )
            {
                /* If the table has been updated such that the focused cell can't be seen - do nothing */
                return;
            }
            _iOldX = aDtPos[ 0 ];
            _iOldY = aDtPos[ 1 ];
        }
        else
        {
            iTableHeight = _nBody.getElementsByTagName('tr').length;
        }

        /* Capture shift+tab to match the left arrow key */
        var iKey = (e.keyCode == 9 && e.shiftKey) ? -1 : e.keyCode;

        switch( iKey )
        {
            case 13: /* return */
                e.preventDefault();
                e.stopPropagation();
                _fnEventFire( "action", _iOldX, _iOldY );
                return true;

            case 27: /* esc */
                if ( !_fnEventFire( "esc", _iOldX, _iOldY ) )
                {
                    /* Only lose focus if there isn't an escape handler on the cell */
                    _fnBlur();
                }
                break;

            case -1:
            case 37: /* left arrow */
                if ( _iOldX > 0 ) {
                    x = _iOldX - 1;
                    y = _iOldY;
                } else if ( _iOldY > 0 ) {
                    x = iTableWidth-1;
                    y = _iOldY - 1;
                } else {
                    /* at start of table */
                    if ( iKey == -1 && _bForm )
                    {
                        /* If we are in a form, return focus to the 'input' element such that tabbing will
                         * follow correctly in the browser
                         */
                        _bInputFocused = true;
                        _nInput.focus();

                        /* This timeout is a little nasty - but IE appears to have some asyhnc behaviour for
                         * focus
                         */
                        setTimeout( function(){ _bInputFocused = false; }, 0 );
                        _bKeyCapture = false;
                        _fnBlur();
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                break;

            case 38: /* up arrow */
                if ( _iOldY > 0 ) {
                    x = _iOldX;
                    y = _iOldY - 1;
                } else {
                    return false;
                }
                break;

            case 9: /* tab */
            case 39: /* right arrow */
                if ( _iOldX < iTableWidth-1 ) {
                    x = _iOldX + 1;
                    y = _iOldY;
                } else if ( _iOldY < iTableHeight-1 ) {
                    x = 0;
                    y = _iOldY + 1;
                } else {
                    /* at end of table */
                    if ( iKey == 9 && _bForm )
                    {
                        /* If we are in a form, return focus to the 'input' element such that tabbing will
                         * follow correctly in the browser
                         */
                        _bInputFocused = true;
                        _nInput.focus();

                        /* This timeout is a little nasty - but IE appears to have some asyhnc behaviour for
                         * focus
                         */
                        setTimeout( function(){ _bInputFocused = false; }, 0 );
                        _bKeyCapture = false;
                        _fnBlur();
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                }
                break;

            case 40: /* down arrow */
                if ( _iOldY < iTableHeight-1 ) {
                    x = _iOldX;
                    y = _iOldY + 1;
                } else {
                    return false;
                }
                break;

            default: /* Nothing we are interested in */
                return true;
        }

        _fnSetFocus( _fnCellFromCoords(x, y) );
        return false;
    }


    /*
     * Function: _fnCaptureKeys
     * Purpose:  Start capturing key events for this table
     * Returns:  -
     * Inputs:   -
     */
    function _fnCaptureKeys( )
    {
        if ( !_bKeyCapture )
        {
            _bKeyCapture = true;
        }
    }


    /*
     * Function: _fnReleaseKeys
     * Purpose:  Stop capturing key events for this table
     * Returns:  -
     * Inputs:   -
     */
    function _fnReleaseKeys( )
    {
        _bKeyCapture = false;
    }



    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Support functions
     */

    /*
     * Function: _fnCellFromCoords
     * Purpose:  Calulate the target TD cell from x and y coordinates
     * Returns:  node: - TD target
     * Inputs:   int:x - x coordinate
     *           int:y - y coordinate
     */
    function _fnCellFromCoords( x, y )
    {
        if ( _oDatatable )
        {
            var oSettings = _oDatatable.fnSettings();
            if ( typeof oSettings.aoData[ oSettings.aiDisplay[ y ] ] != 'undefined' )
            {
                return oSettings.aoData[ oSettings.aiDisplay[ y ] ].nTr.getElementsByTagName('td')[x];
            }
            else
            {
                return null;
            }
        }
        else
        {
            return jQuery('tr:eq('+y+')>td:eq('+x+')', _nBody )[0];
        }
    }


    /*
     * Function: _fnCoordsFromCell
     * Purpose:  Calculate the x and y position in a table from a TD cell
     * Returns:  array[2] int: [x, y]
     * Inputs:   node:n - TD cell of interest
     * Notes:    Not actually interested in this for DataTables since it might go out of date
     */
    function _fnCoordsFromCell( n )
    {
        if ( _oDatatable )
        {
            var oSettings = _oDatatable.fnSettings();
            return [
                jQuery('td', n.parentNode).index(n),
                jQuery('tr', n.parentNode.parentNode).index(n.parentNode) + oSettings._iDisplayStart
            ];
        }
        else
        {
            return [
                jQuery('td', n.parentNode).index(n),
                jQuery('tr', n.parentNode.parentNode).index(n.parentNode)
            ];
        }
    }


    /*
     * Function: _fnSetScrollTop
     * Purpose:  Set the vertical scrolling position
     * Returns:  -
     * Inputs:   int:iPos - scrolltop
     * Notes:    This is so nasty, but without browser detection you can't tell which you should set
     *           So on browsers that support both, the scroll top will be set twice. I can live with
     *           that :-)
     */
    function _fnSetScrollTop( iPos )
    {
        document.documentElement.scrollTop = iPos;
        document.body.scrollTop = iPos;
    }


    /*
     * Function: _fnSetScrollLeft
     * Purpose:  Set the horizontal scrolling position
     * Returns:  -
     * Inputs:   int:iPos - scrollleft
     */
    function _fnSetScrollLeft( iPos )
    {
        document.documentElement.scrollLeft = iPos;
        document.body.scrollLeft = iPos;
    }


    /*
     * Function: _fnGetPos
     * Purpose:  Get the position of an object on the rendered page
     * Returns:  array[2] int: [left, right]
     * Inputs:   node:obj - element of interest
     */
    function _fnGetPos ( obj )
    {
        var iLeft = 0;
        var iTop = 0;

        if (obj.offsetParent)
        {
            iLeft = obj.offsetLeft;
            iTop = obj.offsetTop;
            obj = obj.offsetParent;
            while (obj)
            {
                iLeft += obj.offsetLeft;
                iTop += obj.offsetTop;
                obj = obj.offsetParent;
            }
        }
        return [iLeft,iTop];
    }


    /*
     * Function: _fnFindDtCell
     * Purpose:  Get the coords. of a cell from the DataTables internal information
     * Returns:  array[2] int: [x, y] coords. or null if not found
     * Inputs:   node:nTarget - the node of interest
     */
    function _fnFindDtCell( nTarget )
    {
        var oSettings = _oDatatable.fnSettings();
        for ( var i=0, iLen=oSettings.aiDisplay.length ; i<iLen ; i++ )
        {
            var nTr = oSettings.aoData[ oSettings.aiDisplay[i] ].nTr;
            var nTds = nTr.getElementsByTagName('td');
            for ( var j=0, jLen=nTds.length ; j<jLen ; j++ )
            {
                if ( nTds[j] == nTarget )
                {
                    return [ j, i ];
                }
            }
        }
        return null;
    }



    /* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
     * Initialisation
     */

    /*
     * Function: _fnInit
     * Purpose:  Initialise the KeyTable
     * Returns:  -
     * Inputs:   object:oInit - optional - Initalisation object with the following parameters:
     *   array[2] int:focus - x and y coordinates of the initial target
     *     or
     *     node:focus - the node to set initial focus on
     *   node:table - the table to use, if not given, first table with class 'KeyTable' will be used
     *   string:focusClass - focusing class to give to table elements
     *           object:that - focus
     *   bool:initScroll - scroll the view port on load, default true
     *   int:tabIndex - the tab index to give the hidden input element
     */
    function _fnInit( oInit, that )
    {
        /* Save scope */
        _that = that;

        /* Capture undefined initialisation and apply the defaults */
        if ( typeof oInit == 'undefined' ) {
            oInit = {};
        }

        if ( typeof oInit.focus == 'undefined' ) {
            oInit.focus = [0,0];
        }

        if ( typeof oInit.table == 'undefined' ) {
            oInit.table = jQuery('table.KeyTable')[0];
        }

        if ( typeof oInit.focusClass != 'undefined' ) {
            _sFocusClass = oInit.focusClass;
        }

        if ( typeof oInit.datatable != 'undefined' ) {
            _oDatatable = oInit.datatable;
        }

        if ( typeof oInit.initScroll == 'undefined' ) {
            oInit.initScroll = true;
        }

        if ( typeof oInit.form == 'undefined' ) {
            oInit.form = false;
        }
        _bForm = oInit.form;

        /* Cache the tbody node of interest */
        _nBody = oInit.table.getElementsByTagName('tbody')[0];

        /* If the table is inside a form, then we need a hidden input box which can be used by the
         * browser to catch the browser tabbing for our table
         */
        if ( _bForm )
        {
            var nDiv = document.createElement('div');
            _nInput = document.createElement('input');
            nDiv.style.height = "1px"; /* Opera requires a little something */
            nDiv.style.width = "0px";
            nDiv.style.overflow = "hidden";
            if ( typeof oInit.tabIndex != 'undefined' )
            {
                _nInput.tabIndex = oInit.tabIndex;
            }
            nDiv.appendChild(_nInput);
            oInit.table.parentNode.insertBefore( nDiv, oInit.table.nextSibling );

            jQuery(_nInput).focus( function () {
                /* See if we want to 'tab into' the table or out */
                if ( !_bInputFocused )
                {
                    _bKeyCapture = true;
                    _bInputFocused = false;
                    if ( typeof oInit.focus.nodeName != "undefined" )
                    {
                        _fnSetFocus( oInit.focus, oInit.initScroll );
                    }
                    else
                    {
                        _fnSetFocus( _fnCellFromCoords( oInit.focus[0], oInit.focus[1]), oInit.initScroll );
                    }

                    /* Need to interup the thread for this to work */
                    setTimeout( function() { _nInput.blur(); }, 0 );
                }
            } );
            _bKeyCapture = false;
        }
        else
        {
            /* Set the initial focus on the table */
            if ( typeof oInit.focus.nodeName != "undefined" )
            {
                _fnSetFocus( oInit.focus, oInit.initScroll );
            }
            else
            {
                _fnSetFocus( _fnCellFromCoords( oInit.focus[0], oInit.focus[1]), oInit.initScroll );
            }
            _fnCaptureKeys();
        }

        /*
         * Add event listeners
         * Well - I hate myself for doing this, but it would appear that key events in browsers are
         * a complete mess, particulay when you consider arrow keys, which of course are one of the
         * main areas of interest here. So basically for arrow keys, there is no keypress event in
         * Safari and IE, while there is in Firefox and Opera. But Firefox and Opera don't repeat the
         * keydown event for an arrow key. OUCH. See the following two articles for more:
         *   http://www.quirksmode.org/dom/events/keys.html
         *   https://lists.webkit.org/pipermail/webkit-dev/2007-December/002992.html
         *   http://unixpapa.com/js/key.html
         * PPK considers the IE / Safari method correct (good enough for me!) so we (urgh) detect
         * Mozilla and Opera and apply keypress for them, while everything else gets keydown. If
         * Mozilla or Opera change their implemention in future, this will need to be updated...
         * although at the time of writing (14th March 2009) Minefield still uses the 3.0 behaviour.
         */
        if ( jQuery.browser.mozilla || jQuery.browser.opera )
        {
            jQuery(document).bind( "keypress", _fnKey );
        }
        else
        {
            jQuery(document).bind( "keydown", _fnKey );
        }

        if ( _oDatatable )
        {
            jQuery('td', _oDatatable.fnGetNodes()).click( _fnClick );
        }
        else
        {
            jQuery('td', _nBody).click( _fnClick );
        }

        /* Loose table focus when click outside the table */
        jQuery(document).click( function(e) {
            var nTarget = e.target;
            var bTableClick = false;
            while ( nTarget )
            {
                if ( nTarget == oInit.table )
                {
                    bTableClick = true;
                    break;
                }
                nTarget = nTarget.parentNode;
            }
            if ( !bTableClick )
            {
                _fnBlur();
            }
        } );
    }

    /* Initialise our new object */
    _fnInit( oInit, this );
}
